Missing identifier 'ctz'/'ctzll' when compiling with MSVC and /clr

[Brainy0207]

If I try to use fmt in a MSVC project with /clr enabled, I get the following errors:

1>D:\Temp\ConsoleApplication1\fmt-7.1.3\include\fmt\format-inl.h(2017,11): error C3861: 'ctz': identifier not found
1>D:\Temp\ConsoleApplication1\fmt-7.1.3\include\fmt\format-inl.h(2045,11): error C3861: 'ctzll': identifier not found

Here is a simple example to reproduce these errors:

#define FMT_HEADER_ONLY
#include <fmt/format.h>

int main()
{
}

It seems due to _MANAGED beeing defined in /clr builds, the replacement funtions for 'clz', 'clzll', 'ctz' and 'ctzll' are never defined and missing.

fmt/include/fmt/format.h

Lines 206 to 207 in af56753

	#if FMT_MSC_VER && !defined(FMT_BUILTIN_CLZLL) && \
	!defined(FMT_BUILTIN_CTZLL) && !defined(_MANAGED)

I think the better approach here would be to remove the _MANAGED check and instead force this section to native mode, to be able to use intrinsics without warnings:

// Switch to native
#pragma managed(push,off)
// Do native stuff here
#pragma managed(pop)
// Switch back to previous mode

[vitaut]

I think the better approach here would be to remove the _MANAGED check and instead force this section to native mode, to be able to use intrinsics without warnings

Sure, a PR is welcome.